This astronomy blog chronicles my telescope adventures while waiting for Mars' next opposition in October 2020.
Thursday, December 20, 2018
On December 18th, 2018, Comet 46P/Wirtanen was naked eye visible from my backyard. Just barely.
If you waited for moonset and knew exactly where to look and used averted vision. Yup. There it was. A dim grayish-green splotch in the sky.
It was even better when looking through binoculars. It became a dim green blob.
Then, I aimed the 10 inch Dob at it. It became a much bigger, brighter, but still dim green blob, but now with the increased aperture and magnification, I could see the comet's motion against the starfield.
Using the ZWO ASI294MC imager, I captured this.
46P Zooming by
This data was captured and live stacked with SharpCap. It's 151 frames at 8 seconds exposure, each. So, basically, this is a 20 minute exposure with the starfield being tracked so the relative motion of the comet is apparent.
What if I wanted to track the comet instead of the starfield? It turns out that is a much harder problem. The scope only has tracking modes for lunar, solar, and sidereal.
With the data, I could use DeepSkyStacker for post processing.
I captured over 500 frames of comet data during this session. That ate a lot of room on the hard drive. Clearly, it is now time to increase the size of the storage in the astro laptop. That'll be the subject of a future blog post.
With DeepSkyStacker, I had to mark the comet's position in each one of the data frames. That was pretty tedious, but afterwards I found that it could be done algorithmically if the frames have an embedded date and time stamp.
With that done, I started the stacking process.
Hours later, and with some tweaking, this is the best I could do.
46P Zooming by
The stacked brilliance of the comet swamps the resultant image and color is missing, but you can see the streaks of the starfield!
I will continue to use DeepSkyStacker for post processing data throughout the upcoming year. Who knows what new things I'll learn?